Compositions for topical treatment of acne are known. Smith, U.S. Pat. No. 3,952,099, issued Apr. 20, 1976, discloses compositions for treating acne lesions by topical application of tetracycline antibiotics in a skin penetration vehicle comprising sucrose monooleate, decyl methyl sulfoxide and alcohol.
Stoughton, U.S. Pat. No. 3,969,516, issued July 13, 1976, and Arch. Dermatol., 84 182 (1976), discloses a method for topically treating acne by applying formulations containing various antibiotics in N-methyl-2-pyrrolidone. The data presented are said to indicate that tetracycline in a pyrrolidone-based penetrating vehicle does not effectively control the inflammatory lesions of acne. In addition to tetracycline, compositions of erythromycin, erythromycin derivatives and clindamycin in the same vehicle were studied. The combination of erythromycin and N-methyl-2-pyrrolidone reportedly gave results which were better than tetracycline in the same vehicle, whereas the antibiotic lincomycin gave superior results in controlling the inflamed acne lesions.
In light of the foregoing, it is clear that the effectiveness of any particular antibiotic as a topical treatment of acneiform skin diseases can vary, depending on how well the antibiotic composition penetrates through the skin.
It has been suggested in the scientific literature that zinc ions may be implicated in the biochemical changes associated with wound healing in humans or lower animals. Zinc salts of various antibiotic/antimicrobial agents are known: e.g., zinc undecylenate and zinc bacitracin. U.S. Pat. No. 4,039,681, issued Aug. 2, 1977 teaches the use of zinc methionine to treat acne. German Offenlegungsschrift 2517413, 13/11/75, discloses dermatologic agents containing zinc salts or complexes, and the use of such compositions for treating acne or seborrhoea. Other zinc-containing dermatological compositions, primarily based on zinc oxide, are known: U.S. PHARMACOPOEIA XIX; BRITISH PHARMACOPOEIA 1968; Martindale, THE EXTRA PHARMACOPOEIA 26th Ed.
W. D. Unterman and Th. Mironeanu Acad. Rep. Populare Romine, Filiala, Iasi Studii Cercetari Stiint. Chim. 13(1): 59-66 (1962), describe the chromatographic and electrochromatographic migration of zinc and other metal cations in the presence of antibiotics, including erythromycin. However, the conjoint use of zinc and erythromycin in the manner of this invention does not seem to have been suggested, heretofore.
By the present invention, novel zinc/erythromycin compositions characterized by enhanced skin penetration properties are provided. The compositions herein are suitable for human and veterinary uses. These compositions are especially useful when applied topically in the treatment of "acne", especially Acne vulgaris.